THE INVESTIGATION OF FULLY DEVELOPED FLOW AND HEAT TRANSFER IN RADIATOR AIR CHANNELS

In automotive sector, in order to reduce the space occupied by engine radiators, the use of micro air channels with different cross-sections has been intensified. In these channels both; the hydrodynamic entry-length and the thermal entry-length are small enough compared to the total length of the channel. The flow in the channel occurs in laminar regime and it is plausible to assume it to be hydro-dynamically and thermally fully developed flow. In radiators, despite that several air channels with different cross-sections such as; tetragon, triangle, hexagon, sinusoid, parabola etc. are used, the channels with no sharp corners have advantages from manufacturing point of view and heat transfer point of view. In this study, the convective heat transfer in parabolic, elliptic, sinusoidal and triangular cross-sectioned air channels has been investigated under the condition of constant heat flux. By using appropriate transformations, the solution domains of the momentum and energy equations, which are irregular for numerical solution, were transformed to regular domains like rectangle or square. By conducting case studies for different aspect ratios of air channels, Nusselt number, and the relations between Darcy friction factor and Reynolds number (Poiseuille number) have been determined. The accuracy of the Nusselt number and Poiseuille number were confirmed by comparing with the literature values given for other channels similar to parabolic channels.